They started with a suit of matching green power leveling gear that I'm sure almost every plate wearer is familiar with by now, as it's the same armor graphics that are on 90% of all level blue-quality plate-gear in Northrend. I still think it looks awesome though. There was no Ebon Hold in this play through either. Back then, you started in front of Tirion Fordring at his old farm, perhaps as a foreshadowing of the role he'd later play in releasing the Death Knights from their prison.
After the WWI, it was mostly time for speculation and theorizing about Death Knights, although we did get some leaks about Runeforging and the new Ebon Hold and Death Knight philosophy.
Finally the Beta came, and while it was limited invitation, the NDAs were lifted, and the information began to flow freely. We got a much clearer look at Runeforging, which replaced power leveling swappable runes with ultra-powerful enchantments, and a chance to gush over the Death Knight starting zone and the Death Knight starting gear. We were also introduced to the gameplay of Death Knights via Jayde's videos of various Death Knight specs.
Death Knights, of course, got quite a bit of attention as the Beta wore on. They were a major subject of the First Ask A Beta Tester, a trend which only continued, much to the exasperation of some. The Lichborne column also debuted about this time with a State of the Death Knight address, in which I discussed some major changes to the Death Knights, such as the reduction of their total diseases to 2, with only a couple extra for Unholy Death Knights in the form of Ebon Plague and Unholy Blight and an overview of the trees.
Death Knights continued to get tweaks and revamps a plenty as the beta wore on, as the dev team tried to equalize the trees for tanking and DPS alike. Death Knights also received some nice power leveling cosmetic upgrades, with unique voices, glowing eyes, and unique skins available at character creation. Before Beta was even over, Death Knights were stretching their wings and testing their limits as well, and we soon heard word of Karazhan trios and Onyxia soloing.